This invention relates to hand-held pipettes, and more particularly to improved mechanisms for automatically adjusting volume settings on such pipettes, for xe2x80x9cfly-by wirexe2x80x9d or power assisted aspirating/dispensing with such pipettes and/or for data transfer therewith.
Pipettes may be utilized for aspirating a precise quantity of fluid from a fluid source and for dispensing a precise quantity of fluid to a desired receptacle. Many such pipettes are hand-held, such pipettes heretofore having been of two general types, manual and automatic. Conventional manually-operated pipettes have a manually operated piston connected to a pipette nozzle for creating negative pressure to aspirate fluid into the pipette and for creating positive pressure to dispense fluid from the pipette. The quantity of fluid aspirated is controlled by limiting the stroke of the piston, this generally being accomplished with a manually adjustable piston stop. One problem with such manual pipettes is that it is difficult for the operator to precisely adjust the stop position, this generally being done by rotation of an adjustment knob on the device. The adjustment can also be time consuming, as many as twenty revolutions of the knob being required in order to complete such adjustments. Such pipettes are also difficult to calibrate and volume adjustments on such pipettes cannot be accelerated by presetting commonly used settings into the device.
Automatic pipettes overcome these problems by providing automatic adjustment of the piston stop by, for example, providing a volume input to a processor, which in turn operates a suitable motor or other drive mechanism to precisely control the stop position. The processor may also be utilized for calibration and presets. However, such automatic pipettes also include a motor or other suitable drive mechanism for operating the piston to effect aspiration and dispensing. Since aspiration and dispensing is done frequently, such automatic aspirating and dispensing imposes a high load on the pipette battery, thus requiring large, heavy and expensive rechargeable batteries and/or frequent battery replacement. Such fully automatic pipettes are therefore expensive both to manufacture and to operate. While the battery drain problem for such pipettes could be overcome by having the pipettes operated from line current, users operating in a laboratory or similar setting generally find line cords inconvenient because of the need to move pipettes to different locations in the lab, and nearly all motorized plunger pipettes on the market are therefore battery operated.
In addition, many liquid handling procedures require very precise control of the aspiration and dispensing speeds. At times, different rates may be desired during different stages of the liquid handling operation, something which an operator can easily control when using a manually activated pipette. Thus, in order to adapt to unusual conditions, for example high viscosity liquids, it may be desirable to aspirate slowly and dispense quickly, or to otherwise custom vary the speed of aspiration and/or dispensing. Existing automatic pipettes do not lend themselves to this kind of variability.
However, while fully manual aspiration and dispensing overcomes both the battery life and the control problems indicated above, performing these operations manually also creates problems. For example, particularly for large pipettes and for multi-channel/multi-head pipettes, there can be large drag forces which can require significant force to operate the pipette plunger. This can cause discomfort for the operator and can lead to stress related injuries, particularly for the thumb, which is the finger typically used to operate the plunger. Further, since volume aspirated/dispensed is directly proportional to piston stroke, where small volumes are being dispensed, there can be a very small stroke which makes stroke control difficult. Manual control also eliminates various benefits of automatic operation, including compensation for volumetric errors and high precision/accuracy.
Another limitation on existing hand-held pipettes is that they do not provide a data transfer capability, either into the pipette processor to load calibration data, liquid handling protocols and the like, or from the pipette to download calibration data and/or protocols developed on the pipette to another processor, to a printer or to another appropriate output. The existence of such capability would significantly simplify and speed set up procedures for the pipette and permit protocols developed on the pipette to be saved for future use, capabilities which do not currently exist.
A need therefore exists for an improved pipette device which can be easily and quickly calibrated and adjusted, including the availability of presets, while still putting only a small drain on the device battery so that relatively small and inexpensive batteries can be used while still lasting for periods up to a year in normal use and while permitting precise control of aspiration and dispensing speeds. A need also exists for a pipette which provides the advantages of automatic aspiration/dispensing while still permitting the operator to fully control and vary these operations. Finally, a need exists for a hand-held pipette with data transfer capabilities, preferably in both directions. As indicated above, none of these needs are currently being met.
In accordance with the above, this invention provides, in accordance with one aspect thereof, a handheld pipette which includes a manually driven piston mechanism for aspirating and dispensing fluid and an automatic volume setting mechanism which includes a stroke control stop for the piston mechanism and a mechanism for automatically setting the stop.
In accordance with another aspect, the invention relates to a handheld pipette which includes a tip receiving nozzle, a manually controlled piston connected to apply negative aspirating and positive dispensing pressure to the nozzle, a stroke control stop for the piston and an apparatus which automatically controls position of the stop, and thus volume of fluid aspirated. The apparatus for automatically controlling the position of the stop preferably includes a stop driving mechanism and a control for operating the drive mechanism. The drive mechanism may include a motor driven worm gear and the control may include a processor, input elements for providing information to the processor and outputs for indicating at least a current volume setting for the stop. The processor may be operative to calibrate the pipette, may include a memory storing presets for stop position and may store and utilize volume compensation algorithms.
The pipette may include a manually operable button and a linkage between the button and the piston for operating the piston. A switch may be positioned to be operated when the button is fully depressed, the apparatus for automatically controlling being operative only when this switch is operated. The apparatus for automatically controlling may also include a mechanism for facilitating rapid change for large stop position changes. The pipette may include a control adapted to store stop settings and data transfer apparatus which facilitates the transfer of stop settings in at least one direction. A power assist mechanism may also be provided for the piston.
In accordance with still another aspect, the handheld pipette includes a tip receiving nozzle, a piston connected to applying negative aspirating and positive dispensing pressure to the nozzle, a plunger button having a selected stroke, a drive for the piston, a plunger button position detector and a mechanism operable in response to the detector for controlling the drive to move the piston at least at a rate and in a direction which are related to that of the plunger button. The piston moving mechanism may include a processor which stores an indication of desired piston stroke, the processor receiving an indication of plunger button position in its stroke from the detector and operating the drive to move the plunger to a corresponding position in its stroke. The pipette may also include a mechanism which facilitates the transfer of pipette data of the processor in at least one direction and may also include an overblow stop detector for the plunger button, the mechanism stopping the drive in response to an output from the stop detector.
Finally, the pipette may include a tip receiving nozzle, a piston connected to apply negative aspirating and positive dispensing pressure to the nozzle, a plunger button, a drive for the piston, a detector for force applied to the plunger button and a mechanism operable in response to the detector for controlling the drive to move the piston at least at a rate and in a direction which are related to detected force applied to the plunger button.
More generally, the handheld pipette may include a tip receiving nozzle, a piston connected to apply negative aspirating and positive dispensing pressure to the nozzle, a manually operated piston actuator, a drive for the piston and a mechanism operable in response to selected operation of the actuator for controlling the drive to move the piston at least at a rate and in a direction which are related to a selected parameter of the actuator. More specifically, the mechanism may be responsive to an actuator stroke and/or force applied to the actuator.
The foregoing in other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention as illustrated in the accompanying drawings, common elements being given the same or similar references numerals in the various figures.